EagFirRsp

Our Reference:        2017-10                                       Brisbane Stormwater Management Pty Ltd
                                                                     ACN 094 878 734 ABN 75 094 878 734
                                                                       92 Alkoomie Street, Wynnum Nth, Qld
                                                                         PO Box 8119, Wynnum Nth, Q 4178
Date:       13 October 2017                                                Ph 07 33963383 Mb 0402409604
                                                                             Email: [email protected]




Noosa Council
P O Box 141
Tewantin 4565

Attn:    Mr Patrick Murphy
         Coordinator, Planning & Development Assessment


Dear Sir,

Re:      REC 17/0011, 20 EAGLE DRIVE, TEWANTIN

In response to the Council’s 5 October request for additional information, the XPStorm models have been
revised and the following comments are offered in relation to the stormwater quantity aspects and some of the
basin design aspects of the information request. The relevant parts of the request are highlighted in blue script,
whereas the responses (including some comments on discussions with Council’s reviewer, Premise Consulting)
are in black text.
Modelling Methods

BSM has undertaken a stormwater quantity investigation to design the basin at 14 Eagle Drive. An
XPSTORM model was developed to model the impacts to the whole catchment, the downstream boundary
being where stormwater enters the Noosa Caravan Park from Read Street. The model is calibrated to the
Rational Method calculation with ARR2016 rainfall for the post-development case without the basin. Within
the model, some engine parameters have been changed away from the default values. The SWMM Runoff
Non-linear Reservoir Method was employed in XPSTORM.

We note:

XPSTORM v9.28 was used. It was agreed that Version 9 has the advantage of being a particularly
robust version of the software and, although superseded several times over, can continue to be used.

The default contraction loss has been changed to 0.2 and applied across the model. This was a comment
by Premise rather than an issue. Noted that it was applied globally only to the open channel reaches; -
the piped reaches were individually assigned loss coefficients from QUDM manhole/gully charts.
This was acceptable to Premise.



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BSM Doc File EagFirResp.Doc